I also have an evergreen jasmine climber with round glossy leaves,. about 3.5 ft high, which has lived happily in a large pot on my pation for about 5 years. Last summer I moved it to a different south facing wall and all seemed well.I added plenty of well rotted manure in the autumn. I have just noticed that the leaves and stems are covered by a black coating which washes off with water (in most cases -some leaves are badly stained and can't be cleaned). This is affecting 3/4 of the plant from the bottom upand some of the leaves are yellowing. Please can you advise me what the problem could be. Many thanks, Sue